Alameda County prosecutors declined to file charges Monday against an advertising industry luminary who was arrested last week at Oakland International Airport while wearing an unusual watch that police said resembled a trigger device for a bomb.

The decision not to prosecute Geoffrey McGann, 49, of Rancho Palos Verdes (Los Angeles County), came after he and his attorney professed his innocence, saying the watch he wore Thursday evening was one of dozens he had made and given to friends as art pieces.

McGann was arrested in Terminal 2, after putting the watch through the X-ray scanning machine. The Alameda County Sheriff's Department said it had wires, fuses and a toggle switch, and that McGann also wore a shirt with built-in tourniquets and oversized shoes with hollow compartments in the soles.

McGann, who was jailed on suspicion of possessing bomb-making materials, was released Saturday after posting $150,000 bail.

"Mr. McGann is innocent," Horngrad said on Monday. "He posed no threat to anyone at any time and he meant no threat to anyone at any time. Mr. McGann is an artist and art teacher. Some artists are eccentric, and sometimes act eccentrically. ... He is not an activist or a terrorist."

McGann's homemade watches "are a popular design among people who have seen them," the lawyer added. "Mr. McGann's use of the materials in his watch is completely innocent and artistic."

Sgt. J.D. Nelson, a sheriff's department spokesman, said last week that McGann had flown in from Los Angeles on Thursday morning and was completing his round trip that night. He had no explosive material, but Nelson said the items had to be taken seriously.

"His attorney says he's just misunderstood and I hope that's true," Nelson said. "but if you come into an airport trying to get this device through X-ray screening, art or no art, you should be stopped, questioned and possibly arrested 100 times out of 100.

"Just because someone can make an artsy watch which looks like a timing switch for an IED, doesn't mean it's smart or logical to try to bring it on a plane. Just like you wouldn't bring an artsy fake handgun or an artsy fake hand grenade and try to get that through the security checkpoint."

A spokeswoman for the Alameda County district attorney did not elaborate on the decision not to charge McGann.

McGann is a prominent ad writer and executive who made his name creating ads for Nike, Subaru and other companies. He has taught at the Art Center College of Design in Pasadena, among other schools, and is a fine-art photographer and international jiu-jitsu champion.